You can if you itemize
and the total expenses for you, your spouse, and your dependents exceed
10% of your adjusted gross income (7.5% if you're 65 or older as of
December 31, 2016). The deduction is limited to the expenses above and
beyond this amount.
For example, if you're 48 years old with an AGI of $50,000 and you
incurred $5,900 in medical and dental expenses last year, you could
deduct $900 (the amount in excess of 10% of your AGI, or $5,000),
assuming you're itemizing.
You won't be able to deduct your expenses on your federal return if
you're taking the standard deduction, which about 2/3 of all taxpayers
do.
However, don't let that stop you from entering all your medical-,
dental-, and vision-related expenses anyway. Some states will still let
you deduct these expenses even if you weren't able to deduct them on
your federal return. The expenses must not have been reimbursed (paid
back) by your insurance company.